Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$39.85	11.694%	$44.5101	$44.51	$44.50	$44.50
Purchase #2	$178.85	12.345%	$200.929	$200.93	$200.95	$200.90
Purchase #3	$213.56	13.701%	$242.8199	$242.82	$242.80	$242.80
Purchase #4	$172.33	6.794%	$184.0381	$184.04	$184.05	$184.00
Purchase #5	$89.91	5.105%	$94.4999	$94.50	$94.50	$94.50
Purchase #6	$151.64	7.441%	$162.9235	$162.92	$162.90	$162.90
Purchase #7	$103.32	10.681%	$114.3556	$114.36	$114.35	$114.40
7 purchase totals =	$949.46		$1,044.0761	$1,044.08	$1,044.05	$1,044.00